Method of uniting wires of different sizes.



, I.IT1. FAG/IM vvMETHOD oF UNITIIIIG WIRES 0E DIFFERENT SIZES; APPLICATION `FILED SULY'IZ. |912.

'Patented Nov. 28, 1916.

JOHN T. FAGAN, OF CLEVELAND, OHIO, ASSIGNOR TO GENERAL ELECTRIC COMPANY,

A CORPORATION OF NEW YOBK.

METHOD OF 'UNITING vIIV'IIR'IES OF DIFFERENT SIZES.

4moet..

Specification of 'Letters Patent.

Patented Nov. 2, IOI.

Application filed J'uly 12, 1912. Serial No. 709,054.

To all 'whom z' Mcgraw-ecru.'

Be it known that I, JOHN T. FAGAN, a citizen o f the United States,`residing at Cleveland, county of Cuyahoga, State of Ohio, have invented certain new and useful Improvements in Methods of Uniting Wires of Different Sizes, of which the followingis a specification. l

The object of the present invention is to provide an improved form of sectional leading-in conductor for incandescent lamps, in-

which the sections shall have their joints, or what are commonly called knots, of such diameter as tc-not endanger the efectiveness ofthe seal.

The invention comprises both such a novel form of leading-in conductor or leading-in wire and a novel method for forming the joints of sectional leading-in conductors.

The present application is a continuation in part of my application Serial No. 396,889

filed October 11, v1907, patented July .16,

1912 as Number 1,032,476 entitled, Seals for sectional leading-in wires.

The idea of makingthe leading-in 'wires in sections arose from the necessity of having the wire, atplsome point 1n the seal, of a materialwhich would have substantiallythe same `co-eficient of expansion as glass. A cheap conductor, such as copper, was not available forthis purpose in practice., Platinum was known to have substantially the coelicient of expansion required, but owing to its cost, it was'advisable to use as little as possible. In the earlier forms of lamps short lengths of platinum were led entirely through the glass seal, in which they were embedded and were secured at their ends to the conductors and to the filament. As platinumbecame more and more expensive, cer-.

ing-in wire wasshortened so that the outerl end was embedded in the stem* where end of the copper conductor was joined'thereto, the knot or joint being thus embedded in Qthe Vstem. In a few instances, the platinum sec tion was made 'so short as to be entirely embedded within the glass-seal, and there were secured at the inner ends short sections of copper wire, which were extendedy into the lamp bulb to serve as supports for the filament.

The joints or knotsby which the several sections were united were made before the wires were secured inthe seal. These.knots or joints-were made by fusing the end of the copper conductor until it was suficiently soft to permit one end of the platinum wire to be inserted therein,\and,l by consequence of this procedure, became as well known to every one skilled inthe art, quite appreciably larger than the copper wire itself, and were objectionably large in view of the fact that they were'embedded in the glass seal. rIhis arose from the fact that, upon the fusion of the end of the vcopper wire and the pressing of the small platinum wire into the softened mass, the fused copper, being displaced by the platinum, expanded or spread laterally and gathered' about the platinum in the form of an enlargedbead', which, while making an e'ective electrical joint,vnevertheless was of very markedly greater diameter than the copper wire itself. Further, the form of these joints, wheri completed, has been almost always irregular owing to the fact that the platinum in practically every instance does not exactly strike the center ofl the fused mass when being inserted thereinto, and also owing to other causes which will be pointed out. v

When the end of the platinum wire in approaching the fused copper bead strikes the bead in any way tangentially, the end of the platinum will curl to one side and project to that sidewhen the joint is completed, resulting in a sharp lateral prong which is, when the wires are mounted in the stem, insufficiently covered by the glass. In fact, the glass sometimes is so thin over the projecting pointthat this seal is ine'ective as a vacuum seal, even when first formed. Even should the platinum wire strike the fused copper bead, approximately centrally, it happens that the copper flows or spurts unevenly to one side, resulting in a projecting spur which makes the seal defective'by reason of the glass coat thereover, as in thecase wherein the platinum wire, itself, curls to the side. Since the .thickness of theglass seal is determined in advance bv the xed distance to which the squeezing jaws can approach, it cannot be changed to allow for these uneven and enlarged beads, or vprojections or spurs,

caused by the defective platinum ends and the uneven iiow of fused copper. Therefore, the resulting product, when leading-in wires with such joints are used, is a seal wherein the glass coating or covering is substantially thinner over the jo-ints than over the copper v section itself. This is improper and defective construction, and is the sourceof great loss, and constitutes the reason for the art not having derived that benefit from the original idea of sectional leading-in wires whichcould have been derived therefrom. These unduly enlarged joints and projections being coated or covered at points with a thin skin o-f glass, quite materially thinner than the covering of the body of the copper wire lbehind the joints, which latter covering is .predetermined `by the fixed distance between the squeezing jaws of the machine employed for forming the seal, thus come so close to the surface of the glass as to endanger the seal.

It is the purpose of myinvention to provide electric lamps and other articles, in

which sectional leading-in wiresv may be advantageously employed, with a seal in which the glass covering over the joints is o-fsubstanti'ally the same thickness as the covering'.'over the larger conducting wires, for which latter covering the jaws of the machine are gaged. A l

Referring to the accompanying drawings as illustrating certain embodiments of my invention, Figure 1 is an elevation showing an end Jof the copper conductor with the end of a vplatinum section placed in position lrelatively thereto to form the lmot. Fig. 2 is a cross section taken on the line 2--2 of Fig. l. Fig. 3 is a plan view taken as look-A ing down on Fig. 1. Fig. '4 is a side`elevation showing the joint between `the copper and the platinum sections after the fusion has taken place. Fig. 5 is a cross section taken on the line 5 5 of Fig. 4. Fig. 6 is'` a plan view looking down onFig. 4. Fig. 7 is a cross section showing 'the particular form of copper wire illustrated in Figs. 1,

3, 4, and 6, the line of section being` indicated by the lines 7-7 of these figures.

Fig-.` 8 is across section of a modified form of copper wire, which maybe used in formimg'tlie seal according to my present .invention'. "Fig 9 is a detail cross section showing'the joint embedded in the glass seal. v

In the various forms shown I have prov 'facture -may dictate,-it being essential that this groove, channel, recess or cavity be lo-v cated at the point of formation of the knot or joint. It is essential in order to obtain the best' resultsthat the side walls of the groove be smaller in section than the bottom wall thereof.

. In forming the joint, the end of therplati` num section C is placed within the recess provided in the conducting wire, a suflicient length, and only a suiicient length, of the platinum being placed therein to form the joint successfully, and a fusing iame or arc is then directed onto ythe copper wire at the zone of the joint. lNow, it is well known to those skilled in suchv matter, that if the platinum wire were merely resting against l a fiat or` convex surface of the copper wire,

while the latter was being fused, the surfacel tweenythe platinum sectionand the copper bead would be exceedingly small, and a joint cannot be made in this manner.A By the method which I have devised, however, of providing the conducting wire with-a previously prepared groove, channel, recess or cavity of such contour and proportion that the copper mass will partially envelop the platinum section, when placed therein, the enveloping being of lsuch extent that the fusing and spreading copper at the edges of the groove, channel, recess or cavity will surround and inclose the platinum-section with suiiicient certainty and quickness to overcome the resistance of the surface tension of the fused conducting'wire, which tends to hold the platinumV section away from Athe center of the conductor wire. The effectiveness of this formation is due to the fact that the platinum wire is partially envloped by the copper `so that the expanded fused copper presses upon the sides of the platinumin such direction as to cause the flowingcopper to swell thereover and embed the platinum in its mass; and also to the fact that the mass of copper at the edges ofthe groove, channel, recess or cavity 1s ordinarily of reduced thickness of mass,.and presents a greater surface to the heat so that it fuses more readily than the copper inj the center of the wire, andy therefore has opportunity to envelop the platinum suiciently to hold it, before the copper immediately beneath the platinum becomes fused and expanded sufficiently to lift the latter away' f.

from .the center of the mass.

Obviously, by this method I am enabled to produce a joint in which there is no forf mation of an enlarged copper bead and no displacement of the fused copper by the thrusting in of the platinum, and, consequently, no projectin enlargements or prongs which would endanger the eectiveness of the seal. PThe joint formed remains of substantially the same diameter as that -of the body of the conducting Wire, the cavity or groove being merely lled in. No j expansion of moment, accidental or other- Wise, exists, and the fused glass of the seal may be pressed to the predetermined thinness by the jaws of the seal-forming machine vvithout fear of the glass covering at the seal being thinner over the joint than over the body of the conducting Wire. The thickness of the cover over the body of the conducting Wire is, of course, quite suiicient for the purpose of forming an ecient seal, and there Will be no danger of the glass cover, when of this thickness, being cracked by reason of undue expansion, in vany direcf tion, of the joint.

I claim as Anevv. and Vdesire to secure by. l Letters Patent ofA the United States 1. The methodv of uniting the ends of Wires of different sizes to form a leading-in 2. rlhe method of uniting small Wires ofl dierent sizes to form a leading-in vvirefor an electric incandescent lamp, the larger of said Wires being of more fusible material than the smaller, Which consists in forming a groove at the end of the larger Wire hav? ing its side Walls of smaller cross-section than its bottom Wall, placing the end offthe smaller Wire in the said groove and fusing the said side Walls to embed said smaller Wire. V In Witness vvhereof l". have hereunto set my hand this eleventh day of July, 1912.

y Jonu "r. FAGA'N.

Witnesses WILLIAM W. AMMEN, ARTHUR W. SHERMAN. 

